Teachers stop showing signs of improvement after about four years on the job — even after a master’s degree or obtaining tenure, said Jane Hannaway, founding director of the Education Policy Center at the Urban Institute in Washington, D.C.

“It’s one of our very consistent findings,” said Hannaway, presenter last week at the American Educational Research Association annual meeting in San Diego, citing at least two recent studies of teacher effectiveness.

“The reason of course is not clear, but it’s in study after study,” she said. “Teachers do get better (in the beginning). If you look at the same teacher at Year One, they look a lot better at Year Four but then it flattens out. It’s a puzzle. The real question is why. How can we organize the profession and the work differently?”

Hannaway brought up the topic in a discussion with a small group of journalists during the meeting, saying the results raise deeper questions over the value of tenure and paying teachers incrementally more for every year of service.

Hannaway said the problem could be in poor professional development or in the lack of mentoring and coaching throughout a teacher’s career.

“Why does it flatten out,” she asked, speculating on the reasons. “Teachers work in isolation. They learn what they learn and then they plateau. They get no valid input.”

Student test scores also fail to improve after a teacher receives a master’s degree, she said, specifically citing a study of Teach for America teachers, which you can find here.[1]

The study says:

The findings show that TFA teachers are more effective, as measured by student exam performance, than traditional teachers. Moreover, they suggest that the TFA effect, at least in the grades and subjects investigated, exceeds the impact of additional years of experience, implying that TFA teachers are more effective than experienced secondary school teachers. The positive TFA results are robust across subject areas, but are particularly strong for math and science classes.

The TFA study also shows that having teacher churn is not bad for kids, as long as the person in front of the class is highly effective, she said.

“Typically we have been rewarding teachers for years of service, which is not correlated with effectiveness after the first few years, and graduate coursework and degrees which also do not appear to be related to performance,” Hannaway said in a January presentation to D.C.’s City Council, which you can find here.[2]

The notion turns the teacher compensation system on its head and has not been well received, Hannaway told the journalists.

“A lot of people don’t like these findings,” she said. “We are paying for these different years. But there doesn’t seem to be any returns, at least for test scores.”